Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 301006
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
305 AM PDT WED JUL 30 2014

.SYNOPSIS...AN UPPER LEVEL RIDGE REMAINS ANCHORED OVER THE GREAT
BASIN AND NORTHERN ROCKIES WHILE UPPER LEVEL LOW PRESSURE LINGERS OFF
THE  WEST COAST OF CANADA LEAVING THE PACIFIC NORTHWEST UNDER SOUTH
TO SOUTHWESTERLY FLOW ALOFT. SURFACE LOW PRESSURE EAST OF THE
CASCADES BRINGS WEAK ONSHORE FLOW...ENOUGH TO AFFECT THE IMMEDIATE
COASTAL VALLEYS WHILE THE INTERIOR REMAINS VERY WARM. WEAK
DISTURBANCES LIFTING NORTH FROM CALIFORNIA WILL BRING A CHANCE FOR
THUNDERSTORMS AT TIMES TO THE CASCADES...ESPECIALLY LANE COUNTY.
LITTLE CHANGE EXPECTED IN THIS OVERALL PATTERN THE NEXT SEVERAL DAYS.

&&

.SHORT TERM...THROUGH THURSDAY NIGHT...THE UPPER RIDGE AXIS EXTENDS
FROM IDAHO TO ARIZONA WITH AN UPPER LOW NEAR THE B.C. COAST. THE
PATTERN CHANGES LITTLE DURING THE SHORT TERM PERIOD.  AS A RESULT
VERY WARM WEATHER WILL CONTINUE THROUGH WITH INLAND HIGH TEMPS
RUNNING ABOUT 5 TO 10 DEGREES ABOVE NORMAL. WHILE COASTAL
AREAS REMAIN NEAR NORMAL WITH THE STRONG INFLUENCE OF THE MARINE
LAYER.

THUNDERSTORM THREAT FOR THE OREGON CASCADES WILL VARY OVER THE NEXT
FEW DAYS AS SUBTLE CHANGES IN INSTABILITY AND MOISTURE OCCUR OVER.
THUNDERSTORM ACTIVITY WILL BE LOWER TODAY AS MOISTURE IS LACKING AND
INSTABILITY BELOW 500 MB IS LOW. THE LANE COUNTY CASCADES APPEAR TO
HAVE THE BEST CHANCES FOR CONVECTION TODAY AND THIS EVENING AS VORT
MAX CLIPS THE AREA.  BETTER CHANCES FOR THU/THU NIGHT AS THE REMNANT
MOISTURE OF POST-TROPICAL CYCLONE HERNAN LIFT NORTH AND POSSIBLY
COMBINE WITH ONE OF THE WEAK SHORTWAVES OFFSHORE OF THE CALIFORNIA
COAST. NAM VERTICAL MOISTURE HAS BEEN MORE INLINE WITH OBSERVATIONS
SO WILL LEAN TOWARD ITS HIGH MOISTURE VALUES. THE HIGH OREGON
CASCADES ARE THE MOST LIKELY AREA TO GET THE THUNDERSTORMS. HOWEVER
IT IS NOT OUT OF THE QUESTION AREAS FURTHER WEST COULD BE AFFECTED IF
THE SHORTWAVE BECOMES STRONG ENOUGH TO PULL IN SOME SE FLOW ALOFT.
FOR NOW...JUST INCREASED POPS A BIT ALONG THE
CREST OF THE OREGON CASCADES THU/THU NIGHT.  SIMILAR THREAT FOR
THUNDERSTORMS FOR THE OREGON CASCADES RETURN FRI AFTERNOON. WEAGLE/MH

LONG TERM...FRIDAY NIGHT THROUGH TUESDAY. OUR AREA IS ON THE WEST
SIDE OF  AN UPPER-LEVEL RIDGE OVER THE WESTERN CONUS. SEVERAL
SHORTWAVES ARE FORECAST TO MOVE UP THIS RIDGE AND BRING CHANCES FOR
THUNDERSTORMS ALONG THE CASCADE CREST. THIS RIDGE WILL REMAIN
STATIONARY THROUGH TUESDAY. UNCERTAINTY REMAINS FOR TIMING AND
LOCATION OF THUNDERSTORMS...BUT LOOKS LIKE BEST CHANCE WILL STAY
ALONG THE CASCADE CREST. THE STATIONARY NATURE OF THIS WEATHER
PATTERN WILL KEEP HIGH AND LOW TEMPERATURES FAIRLY PERSISTENT UNTIL
THIS UPPER-LEVEL RIDGE EITHER BREAKS DOWN OR MOVES OFF TO THE EAST.
-MCCOY

&&

.AVIATION...STRATUS AND FOG REMAINING ALONG THE COASTLINE WITH IFR
AND LOCAL LIFR PERSISTING THROUGH LATER THIS MORNING. SOME OF THIS
STRATUS LOOKS TO CONTINUE PUSHING UP THE LOWER COLUMBIA...WITH
CIGS AROUND 1000 FT MAKING IT TO KKLS. EXPECT THIS PUSH TO
CONTINUE TOWARDS THE PORTLAND METRO TERMINALS...WITH CIGS LIKELY
FORMING AT KSPB BUT STILL LESS CONFIDENCE THAT PUSH WILL MAKE IT
TO KPDX OR KTTD. ANY STRATUS INLAND SHOULD CLEAR BY 17Z
TODAY...WITH THE COASTAL AREAS IMPROVING TO VFR BY EARLY
AFTERNOON. STRATUS MAY MAKE A RETURN TO THE COAST THIS
EVENING...THOUGH PERHAPS NOT UNTIL AFTER 06Z NEAR KAST. ELSEWHERE
ACROSS THE INTERIOR...VFR CONDITIONS NEXT 24 HOURS.

KPDX AND APPROACHES...VFR PREVAILING THROUGH AT LEAST 12Z. LOW
MVFR TO HIGH IFR STRATUS MAY APPROACH THE TERMINAL FROM THE W AFT
12Z...BUT CONFIDENCE REMAINS SOMEWHAT LOW. ANY CIGS THAT DO FORM
SHOULD CLEAR BY 16Z WITH VFR THEREAFTER.  CULLEN

&&

.MARINE...LITTLE CHANGE TO THE OVERALL PATTERN TODAY AS HIGH PRES
IS FIRMLY IN CONTROL OVER THE NE PAC. MEANWHILE...THE THERMAL
TROUGH REMAINS OVER N CALIFORNIA AND WILL RISE SLIGHTLY N IN THE
AFTERNOON/EVENING HOURS. THIS WILL INCREASE THE PRESSURE GRADIENT
A BIT OVER THE OREGON WATERS WITH GUSTIER WINDS...TO AROUND 25 KT
AT TIMES. ISSUED SMALL CRAFT ADVISORY FOR WINDS FOR THE SOUTHERN
WATERS AND NORTHERN INNER WATERS... WITH STRONGEST WINDS MOSTLY S
OF TILLAMOOK.

SEAS WILL CONTINUE TO PRIMARILY BE A MIXTURE OF WIND WAVE AND
FRESH SWELL...AND INDISTINGUISHABLE AT TIMES...SO CONTINUED TO
COMBINE THE SEAS THROUGH THE FORECAST PERIOD. SEAS WILL REMAIN
STEEP AND IN THE 4 TO 6 FT RANGE THROUGH THE WEEK...THROUGH COULD
INCREASE TO CLOSE TO 7 FT AT TIMES WITH THE STRONGEST WINDS. SEAS
WILL BE STEEPEST WHEN THE WINDS ARE THE STRONGEST...DURING THE
AFTERNOON AND EVENING HOURS...PARTICULARLY S OF TILLAMOOK AND
NEAR SHORE. CULLEN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 11 AM THIS MORNING TO 11 PM
     PDT THIS EVENING FOR COASTAL WATERS FROM CAPE SHOALWATER WA
     TO CASCADE HEAD OR OUT 10 NM AND COASTAL WATERS FROM CASCADE
     HEAD OR TO FLORENCE OR OUT 60 NM.

&&

$$

MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.


&&



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